20402157 has 4 divisors (see below), whose sum is σ = 27202880. Its totient is φ = 13601436.

The previous prime is 20402153. The next prime is 20402189. The reversal of 20402157 is 75120402.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 20402157 - 2² = 20402153 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20402153) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3400357 + ... + 3400362.

It is an arithmetic number, because the mean of its divisors is an integer number (6800720).

Almost surely, 2^20402157 is an apocalyptic number.

It is an amenable number.

20402157 is a deficient number, since it is larger than the sum of its proper divisors (6800723).

20402157 is an equidigital number, since it uses as much as digits as its factorization.

20402157 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6800722.

The product of its (nonzero) digits is 560, while the sum is 21.

The square root of 20402157 is about 4516.8746938564. The cubic root of 20402157 is about 273.2490716210.

Adding to 20402157 its reverse (75120402), we get a palindrome (95522559).

The spelling of 20402157 in words is "twenty million, four hundred two thousand, one hundred fifty-seven".